senrec_ex.java

刘艺编著的java教程的课本习题加例题代码 很有用哦！

class Databuf{ 
 private int value;
 private boolean writeable=true;
 int sort=0;
 synchronized void senddata(){
   while(!writeable)
    try{
     this.wait();
    }
    catch(InterruptedException e){
     System.out.println(e);
    }
   value=(int)(Math.random()*10);
   writeable=false;
   notifyAll();
 }
 synchronized int receivedata(int num){
  while(writeable||sort%4+1!=num)
   try{
    this.wait();
   }
   catch(InterruptedException e){
    System.out.println(e);
   }
  sort=sort+1;
  writeable=true;
   //notifyAll(); 
  notify();//which statement is correct
  return value;
 }
 int getvalue(){
   return value;
 }
}
class Send extends Thread{
 Databuf da;
 public Send(Databuf d){
   da=d;
 }
 public void run(){
  int i;
  synchronized(da){ 
   for(i=1;i<=4;i++){ 
     try{
      sleep(1);
     }
     catch(InterruptedException e){
      System.out.println(e);
     }
     da.senddata(); 
     System.out.println("Send data"+i+": "+da.getvalue());
   }
  }
 }
}
class Receive extends Thread{
 Databuf da;
 int num;
 public Receive(Databuf d,int n){
  da=d; 
  num=n;
 }
 public void run(){
  synchronized(da){
    try{
     sleep(1);
    }
    catch(InterruptedException e){
     System.out.println(e);
    }
    System.out.println("Number"+num+" get data:  "+da.receivedata(num));
  }
 }
}
public class SenRec_ex{
 public static void main(String args[]){
  Databuf da=new Databuf();
  Send s1=new Send(da);
  Receive r1=new Receive(da,1);
  Receive r2=new Receive(da,2);
  Receive r3=new Receive(da,3);
  Receive r4=new Receive(da,4);
  s1.start();
  r1.start();
  r2.start();
  r3.start();
  r4.start();
 }
}